As known to those in the art of microwave radio communications, an orthomode transducer (OMT) is a three-port device which can be used to separate and/or combine orthogonally polarized signals. The OMT is often used to receive signals of a first polarization and transmit signals of a second polarization. The OMT includes a housing that defines a waveguide including a first waveguide branch, a second waveguide branch coupled to the first waveguide branch, and a third waveguide branch coupled to the first and second waveguide branches. The first waveguide branch is configured to enable propagation of a signal having the first polarization. The second waveguide branch is configured to enable propagation of a signal having the second polarization. The third waveguide branch is configured to enable propagation of a signal having either the first polarization or the second polarization.
Microwave radio communication systems can operate over a wide range of frequencies (from 5 GHz to 80 GHz, for example). It is therefore necessary to provide OMTs that operate over many different frequencies. Because the size and/or configuration (e.g., shape) of the waveguide in an OMT varies with frequency, traditionally, several OMTs with differently sized waveguides need to be provided to cover all of the frequencies required for certain applications.
FIG. 1 shows a conventional OMT assembly 10. The assembly 10 includes a frame 20 and an OMT 30 secured to the frame 10. The OMT 30 is constructed of a machined block of material, such as aluminum or magnesium, and defines an internal waveguide (not shown). The OMT 30 includes a first port 40 including a first waveguide aperture 42 in a first side 30a of the OMT 30, a second port including a second waveguide aperture (not shown) in a second side 30b of the OMT 30 opposite the first side 30a, and a third port 60 including a third waveguide aperture 62 located at an end 30c of the OMT30. The first waveguide aperture 42 is located at an external end of a first waveguide branch (not shown) configured to enable propagation of a signal having a first polarization. The second waveguide aperture (not shown) is located at an external end of a second waveguide branch (not shown) configured to enable propagation of a signal having a second polarization. The third waveguide aperture 62 is located at an external end of a third waveguide branch (not shown) configured to enable propagation of a signal having either the first polarization or the second polarization.
Still referring to FIG. 1, radios (not shown) can be attached to first port 40 and the second port (not shown) to place the radios in communication with the first waveguide aperture 42 and the second waveguide aperture (not shown), respectively. A feed element mounting assembly 70 can be attached to the third port 60 to place a feed element or feed horn (not shown) in communication with the third waveguide aperture 62.
The assembly 10 is relatively expensive to manufacture, as it employs two parts (the frame 20 and the OMT 30), and machining of the OMT 30 (particularly, the waveguide) is expensive. Additionally, the assembly 10 is customer/application specific and, therefore, the frame 20 must be configured differently for each customer/application.
In view of the above, it is desirable to provide cost-effective methods of manufacturing OMTs having a wide range of operating frequencies. It is further desirable to provide OMTs that have a substantially consistent outer housing shape and size regardless of operating frequency.